Capillary valve structure and microfluidic chip

Abstract

The application relates to a capillary valve structure and a micro-fluidic chip. The capillary valve structure comprises a first capillary valve, a second capillary valve, a burst valve assembly and a third capillary valve which are sequentially connected; the first capillary valve is configured to also communicate with a first chamber, and the third capillary valve is configured to also communicate with a second chamber, so as to transfer liquid in the first chamber to the second chamber under centrifugal action; the length of the burst valve assembly is greater than the lengths of the second capillary valve and the third capillary valve, and the length of the second capillary valve is greater than the length of the first capillary valve. The capillary valve structure overcomes the shortcomings of traditional capillary valves, avoids the problem of backflow of liquid along the capillary valve structure in a centrifugal environment, thereby avoiding backflow of liquid between chambers of the micro-fluidic chip, and further ensuring the expected control effect of micro-fluidics and improving the control ability of the micro-fluidic chip on liquid; the capillary valve structure has a simple overall structure, and only needs to control the on-off of liquid through a centrifugal rate, so that the capillary valve structure is easy to apply to a micro-fluidic chip and realize valve control function in cooperation with other functional chambers.

Description

Technical Field

[0001] This application relates to the field of microfluidics, and in particular to capillary valve structures and microfluidic chips. Background Technology

[0002] Microfluidics is typically implemented using microfluidic chips, which are microanalytical systems that integrate sample pretreatment, mixing, reaction, separation, and detection operations into one or more chips to replace traditional laboratory work.

[0003] Microfluidic chips have the advantages of requiring small sample volumes, being simple to operate, and being able to accurately complete the entire process from sample preparation to result display in a short time, effectively overcoming experimental errors caused by manual operation in traditional laboratory work.

[0004] Therefore, microfluidic chips are increasingly being used in fields such as chemical analysis, DNA sequencing, protein analysis, single-cell analysis, single-molecule analysis, food safety, environmental monitoring, and drug screening.

[0005] Microfluidic chips typically use capillary valves as channel switches. Capillary valves control the flow of liquid by changing the capillary pressure through abrupt changes in the geometry of the microchannel. Traditional capillary valves are mostly straight-through type.

[0006] However, it was found during use that microfluidic chips, especially disk-type microfluidic chips, have a series of events such as rapid acceleration, sudden stop, and continuous forward and reverse rotation during operation. At this time, the liquid in the cavity is under the action of a large Euler force, that is, the inertial force caused by angular acceleration, and is easy to flow back through the capillary valve and back into the previous cavity. Summary of the Invention

[0007] Therefore, it is necessary to provide a capillary valve structure and a microfluidic chip.

[0008] One embodiment of this application is a capillary valve structure, which includes a first capillary valve, a second capillary valve, a burst valve assembly, and a third capillary valve connected in sequence.

[0009] The first capillary valve is configured to also connect to the first chamber, and the third capillary valve is configured to also connect to the second chamber, so as to transfer liquid in the first chamber to the second chamber under centrifugal force;

[0010] The length of the burst valve assembly is greater than the lengths of the second capillary valve and the third capillary valve, and the length of the second capillary valve is greater than the length of the first capillary valve.

[0011] The aforementioned capillary valve structure, employing a cooperating first capillary valve, second capillary valve, burst valve assembly, and third capillary valve, serves several purposes. Firstly, it replaces traditional capillary valves, controlling the flow of liquid by altering capillary pressure through abrupt changes in microchannel geometry. Secondly, it overcomes the shortcomings of traditional elongated or N-shaped capillary valves, preventing backflow of liquid along the capillary valve structure in centrifugal environments. This avoids backflow between microfluidic chip chambers, ensuring the expected control effect of microfluidics and improving the microfluidic chip's ability to control liquids. Furthermore, the capillary valve structure is simple overall, controlling liquid flow solely through centrifugation speed without requiring additional heating or electrical control, making it easy to apply to microfluidic chips and other functional chambers to achieve valve control functions.

[0012] In some embodiments, the sum of the volumes of the first capillary valve, the second capillary valve, and the third capillary valve is less than the volume of the burst valve assembly; or,

[0013] The maximum passing area of ​​any one of the first capillary valve, the second capillary valve, and the third capillary valve is less than the maximum passing area of ​​the burst valve assembly.

[0014] In some embodiments, the expansion angle between the first capillary valve and the first chamber is greater than or equal to 45°; or,

[0015] The expansion angle between the second capillary valve and the burst valve assembly is greater than or equal to 45°; or,

[0016] The expansion angle of the third capillary valve and the burst valve assembly is greater than or equal to 45°; or,

[0017] The expansion angle between the third capillary valve and the second chamber is greater than or equal to 45°.

[0018] In some embodiments, the first capillary valve and the second capillary valve have the same or different bending shapes, and the bending shape has at least one inflection point; or,

[0019] At least one of the first capillary valve and the second capillary valve has a hydrophobic surface; or,

[0020] The third capillary valve has a hydrophobic surface.

[0021] In some embodiments, the length of the first capillary valve is 10 μm to 100 μm; or,

[0022] The length of the second capillary valve is 50 μm to 1000 μm; or,

[0023] The length of the third capillary valve is 100 μm to 1000 μm.

[0024] In some embodiments, the maximum passage area of ​​the burst valve assembly is greater than 1 square millimeter; and / or,

[0025] The length of the rupture valve assembly is 0.5 mm to 5 mm;

[0026] In some embodiments, the burst valve assembly includes a burst valve and a buffer chamber, the buffer chamber being connected to the second capillary valve, the burst valve, and the third capillary valve, respectively.

[0027] In some embodiments, the buffer cavity is flat and short in the centrifugal radial direction.

[0028] In some embodiments, the capillary valve structure further includes at least one of the first chamber and the second chamber.

[0029] In some embodiments, a microfluidic chip includes a substrate and a capillary valve structure as described in any embodiment, the capillary valve structure being disposed on the substrate. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of one embodiment of the capillary valve structure described in this application.

[0032] Figure 2 For adopted Figure 1 A schematic diagram of one embodiment of the microfluidic chip shown in the illustration.

[0033] Reference numerals: capillary valve structure 100, first chamber 110, first capillary valve 120, second capillary valve 130, burst valve 140, buffer chamber 150, third capillary valve 160, second chamber 170, inflection point 180, microfluidic chip 200, substrate 210, rotation center 220. Detailed Implementation

[0034] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0035] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application's specification are for illustrative purposes only and do not represent the only possible implementation.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0037] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0038] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and or" as used in this application includes any and all combinations of one or more of the associated listed items.

[0039] In one embodiment of this application, a capillary valve structure 100 is as follows: Figure 1As shown, it includes a first capillary valve 120, a second capillary valve 130, a burst valve assembly, and a third capillary valve 160 connected in sequence; the first capillary valve 120 is configured to also connect to a first chamber 110, and the third capillary valve 160 is configured to also connect to a second chamber 170, so as to transfer liquid in the first chamber 110 to the second chamber 170 under centrifugal force; the length of the burst valve assembly is greater than the length of the second capillary valve 130 and the third capillary valve 160, and the length of the second capillary valve 130 is greater than the length of the first capillary valve 120.

[0040] This design, employing a first capillary valve 120, a second capillary valve 130, a burst valve assembly, and a third capillary valve 160 in a coordinated manner, serves two main purposes. First, it replaces traditional capillary valves, effectively controlling the flow of liquid by altering the capillary pressure through abrupt changes in the microchannel geometry. Second, it overcomes the shortcomings of traditional elongated or N-shaped capillary valves, preventing backflow of liquid along the capillary valve structure 100 in a centrifugal environment. This avoids backflow between microfluidic chip chambers, ensuring the expected control effect of microfluidics and improving the microfluidic chip's ability to control liquids. Third, the capillary valve structure 100 has a simple overall structure, controlling the flow of liquid solely through centrifugation speed, eliminating the need for additional heating or electrical control of the valves. This makes it easy to apply to microfluidic chips and other functional chambers to achieve valve control functions.

[0041] In various embodiments, the first capillary valve 120 is further connected to the first chamber 110, and the third capillary valve 160 is further connected to the second chamber 170, so as to transfer the liquid in the first chamber 110 to the second chamber 170 under centrifugal force. That is, the first chamber 110 is connected to the second chamber 170 through the first capillary valve 120, the second capillary valve 130, the burst valve assembly, and the third capillary valve 160. In some embodiments, the capillary valve structure 100 further includes at least one of the first chamber 110 and the second chamber 170. In some embodiments, the capillary valve structure 100 further includes the first chamber 110 and the second chamber 170. In specific applications, combined with Figure 2 Other chambers of the microfluidic chip 200, such as the liquid storage chamber, can be connected to the first capillary valve 120 as the first chamber 110, or can be directly or indirectly connected to the first chamber 110; similarly, other chambers of the microfluidic chip 200, such as the buffer chamber, reaction chamber, or waste liquid chamber, can be connected to the third capillary valve 160 as the second chamber 170, or can be directly or indirectly connected to the second chamber 170.

[0042] This design, on the one hand, allows the capillary valve structure 100 (excluding the first chamber 110 and the second chamber 170) to form a complete flow path together with the first chamber 110 and the second chamber 170. The directional transfer of liquid from the first chamber 110 to the second chamber 170 can be completed solely by centrifugal force, eliminating the need for external pumps, solenoid valves, or other active driving components, thus significantly simplifying the fluid control system of the microfluidic chip 200. On the other hand, the capillary valve structure 100 can also flexibly integrate the first chamber 110 and the second chamber 170, adapting to various functional chambers such as storage chambers, buffer chambers, reaction chambers, and waste chambers, accommodating the diverse process requirements of the microfluidic chip 200 and improving the versatility and scalability of the chip layout. Furthermore, the complete connection path of the capillary valve structure 100, combined with multi-stage capillary valves and burst valve components, enhances the unidirectional fluid conduction capability under centrifugal conditions, preventing backflow and countercurrent between the first chamber 110 and the second chamber 170, ensuring stable and controllable fluid timing. On the other hand, the modular chamber connection method reduces the difficulty of chip processing and assembly, improves batch consistency, and is suitable for real-time detection scenarios such as POCT, making it easier to implement the capillary valve structure 100 in the microfluidic chip 200, and stably realize multi-step liquid transfer and valve control timing functions.

[0043] In each embodiment, such as Figure 1 As shown, the length of the burst valve assembly is greater than the lengths of the second capillary valve 130 and the third capillary valve 160, and the length of the second capillary valve 130 is greater than the length of the first capillary valve 120, to prevent liquid backflow. Combined with... Figure 2 As an example, the length is the radial length of the microfluidic chip 200, that is, the difference in distance from the radial direction to the rotation center 220. In other embodiments, the length is the length through which the liquid flows, also known as depth. To improve backflow prevention, as an example, the length ratio of the burst valve assembly to the second capillary valve 130 is greater than 3; as an example, the length ratio of the second capillary valve 130 to the first capillary valve 120 is greater than 1.5; as an example, the length ratio of the burst valve assembly to the third capillary valve 160 is greater than 3. As an example, the length ratio of the third capillary valve 160 to the second capillary valve 130 is greater than 2.

[0044] This graded length ratio and radial dimension design, on the one hand, through a clear length gradient constraint—that is, the length of the burst valve assembly is greater than the lengths of the second capillary valve 130 and the third capillary valve 160, and the length of the second capillary valve 130 is greater than the length of the first capillary valve 120—combined with the design of the distance difference between the radial length of the microfluidic chip 200 and the rotation center 220, precisely constructs a progressively increasing capillary pressure barrier. This fundamentally blocks the backflow of liquid along the capillary valve structure 100 under centrifugal conditions, reliably preventing liquid backflow between chambers and stably maintaining the unidirectional fluid transmission order. On the other hand, by making the length definition compatible with the radial distance difference and the liquid flow length and depth, it adapts to different chip structures and flow path processing schemes, improving the design flexibility and process compatibility of the capillary valve structure 100. On the other hand, by setting quantitative ratios such that the length ratio of the rupture valve assembly to the second capillary valve 130 is greater than 3, the length ratio of the second capillary valve 130 to the first capillary valve 120 is greater than 1.5, the length ratio of the rupture valve assembly to the third capillary valve 160 is greater than 3, and the length ratio of the third capillary valve 160 to the second capillary valve 130 is greater than 2, the backflow prevention threshold is further strengthened, the stability and repeatability of fluid control are improved, and the interference caused by centrifugal speed fluctuations is reduced.

[0045] To further prevent backflow of liquid along the capillary valve structure 100 in a centrifugal environment, in some embodiments, the first capillary valve 120 has a length of 10 μm to 100 μm; and / or, in some embodiments, the second capillary valve 130 has a length of 50 μm to 1000 μm; and / or, in some embodiments, the third capillary valve 160 has a length of 100 μm to 1000 μm. As an example, the first capillary valve 120 has a length of 30 μm; the second capillary valve 130 has a length of 60 μm; and the third capillary valve 160 has a length of 200 μm. In some embodiments, the burst valve assembly has a length of 0.5 mm to 5 mm. As an example, the burst valve assembly or its buffer chamber 150, which will be described below, has a length of 1 mm.

[0046] This refined dimensional parameter design, on the one hand, involves graded and quantified constraints on the first capillary valve 120, the second capillary valve 130, the third capillary valve 160, and the burst valve assembly. Combined with specific length constraints within ranges such as 10μm to 100μm, 50μm to 1000μm, 100μm to 1000μm, and 0.5mm to 5mm, and typical example values ​​of 30μm, 60μm, 200μm, and 1mm, it precisely constructs a capillary pressure gradient matching the centrifugal force field. This further prevents backflow of liquid along the capillary valve structure 100 under centrifugal conditions, completely eliminating the risk of liquid backflow between chambers and ensuring stable and reliable fluid transmission in the microfluidic chip 200. On the other hand, the clearly defined dimensional ranges and typical values ​​significantly improve the reproducibility and process feasibility of the flow path design, reduce the impact of micromachining tolerances on valve control performance, and improve consistency in mass production. On the other hand, combined with the length matching design of the buffer chamber 150, the fluid conduction timing and flow stabilization effect can be optimized in a coordinated manner, effectively avoiding fluid impact and bubble trapping, which is conducive to maintaining the consistency and repeatability of passive valve control of the capillary valve structure 100.

[0047] In some of these embodiments, such as Figure 1 As shown, the burst valve assembly includes a burst valve 140 and a buffer chamber 150, the buffer chamber 150 being connected to the second capillary valve 130, the burst valve 140, and the third capillary valve 160, respectively. To further prevent backflow of liquid along the capillary valve structure 100 in a centrifugal environment, combined with... Figure 2As an example, the maximum distance between the burst valve 140 and the rotation center 220 is less than the maximum distance between the buffer chamber 150 and the rotation center 220; and the minimum distance between the burst valve 140 and the rotation center 220 is also less than the minimum distance between the buffer chamber 150 and the rotation center 220. Traditional capillary valves can only achieve on / off switching, while this embodiment, through the combination of the burst valve 140 and the buffer chamber 150, achieves passive fluid control with precise timing, eliminating the need for external drives such as heating, thus solving a core pain point in the automation of microfluidic chips. As an example, the specifications of the burst valve 140, such as the burst pressure, can be precisely controlled through channel size and surface modification to achieve sequential triggering of multi-step reactions. The buffer design of the buffer chamber 150 avoids bubble trapping and flow interruption, improving the reliability and repeatability of the capillary valve structure 100 and the microfluidic chip 200 using the burst valve 140 and buffer chamber 150. This fully passive structure significantly reduces the manufacturing cost and usage threshold of the microfluidic chip 200, making it suitable for point-of-care testing (POCT) and other application scenarios. In contrast, traditional capillary valves do not involve the design of the buffer chamber 150, ignoring the impact of fluid impact on the downstream flow path. The relevant embodiments of this application use a burst valve assembly to achieve functions such as trigger conduction, flow stabilization buffering, and backflow buffering.

[0048] To further prevent backflow of liquid along the capillary valve structure 100 in a centrifugal environment, in some embodiments, the sum of the volumes of the first capillary valve 120, the second capillary valve 130, and the third capillary valve 160 is less than the volume of the burst valve assembly; and / or, in some embodiments, the maximum flow area of ​​any one of the first capillary valve 120, the second capillary valve 130, and the third capillary valve 160 is less than the maximum flow area of ​​the burst valve assembly. For an embodiment with a buffer chamber 150, as an example, the sum of the volumes of the first capillary valve 120, the second capillary valve 130, and the third capillary valve 160 is less than the volume of the buffer chamber 150; and / or, the maximum flow area of ​​any one of the first capillary valve 120, the second capillary valve 130, and the third capillary valve 160 is less than the maximum flow area of ​​the buffer chamber 150.

[0049] This volume and flow area ratio design, on the one hand, controls the sum of the volumes of the first capillary valve 120, the second capillary valve 130, and the third capillary valve 160 to a level smaller than the volume of the burst valve assembly, while ensuring that the maximum flow area of ​​any one of the three channels is smaller than the maximum flow area of ​​the burst valve assembly. This creates a stable fluid pressure difference and a unidirectional flow barrier in the centrifugal flow field, further preventing backflow of liquid along the capillary valve structure 100. Structurally, it completely avoids liquid backflow between the chambers of the microfluidic chip 200, ensuring precise and controllable fluid transmission direction and timing. On the other hand, in the embodiment with the integrated buffer chamber 150, setting the total volume of the three-stage capillary valves to be smaller than the volume of the buffer chamber 150 and the maximum flow area of ​​each capillary valve to be smaller than the maximum flow area of ​​the buffer chamber 150 effectively improves fluid capacity and buffering capacity, weakens the impact effect caused by high-speed liquid flow, avoids flow path interruption and bubble trapping, and significantly improves the operational stability and detection repeatability of the capillary valve structure 100.

[0050] To further prevent backflow of liquid along the capillary valve structure 100 in a centrifugal environment, in some embodiments, the maximum flow area of ​​the burst valve assembly is greater than 1 square millimeter; in some embodiments, the maximum flow area of ​​the burst valve assembly is greater than 1 square millimeter, and the length of the burst valve assembly is 0.5 mm to 5 mm. For embodiments with a buffer chamber 150, as an example, the maximum flow area of ​​the buffer chamber 150 is greater than 1 square millimeter; as an example, the length of the buffer chamber 150 is 0.5 mm to 5 mm. In some embodiments, such as... Figure 1 As shown, the buffer cavity 150 is flat and has a shorter length in the centrifugal radial direction. That is, in the radial direction of the microfluidic chip 200, the length of the buffer cavity 150 is less than the length in the circumferential direction of the microfluidic chip 200.

[0051] This structural parameter and shape design, on the one hand, by setting the maximum flow area of ​​the burst valve assembly to be greater than 1 square millimeter, and combining it with a length range of 0.5 mm to 5 mm, forms a flow capacity and pressure threshold suitable for fluid transmission under centrifugal conditions, further preventing backflow of liquid along the capillary valve structure 100, reliably avoiding liquid backflow between the first chamber 110 and the second chamber 170, and ensuring unidirectional and orderly fluid transmission of the microfluidic chip 200. On the other hand, in the embodiment including the buffer chamber 150, setting the maximum flow area of ​​the buffer chamber 150 to be greater than 1 square millimeter and controlling the length to 0.5 mm to 5 mm can significantly improve the fluid buffering and temporary storage capacity, weaken the impact of high-speed liquid flow, prevent flow path interruption and bubble trapping, and improve the working stability and detection repeatability of the capillary valve structure 100. On the other hand, the buffer cavity 150 adopts a flat shape, and its radial length in the microfluidic chip 200 is less than its circumferential length. This can optimize the force distribution of the flow channel within the limited chip space, which is beneficial to reduce the disturbance of the centrifugal force field on the fluid direction, further enhance the anti-backflow effect of the capillary valve structure 100, and effectively improve the space utilization of the microfluidic chip 200.

[0052] To further prevent backflow of liquid along the capillary valve structure 100 in a centrifugal environment, in some embodiments, the expansion angle between the first capillary valve 120 and the first chamber 110 is greater than or equal to 45°; for example, the expansion angle between the first capillary valve 120 and the first chamber 110 is greater than or equal to 50°. In some embodiments, the expansion angle between the second capillary valve 130 and the burst valve assembly is greater than or equal to 45°; for example, the expansion angle between the second capillary valve 130 and the burst valve assembly is greater than or equal to 50°. In some embodiments, the expansion angle between the third capillary valve 160 and the burst valve assembly is greater than or equal to 45°; for example, the expansion angle between the third capillary valve 160 and the burst valve assembly is greater than or equal to 50°. For embodiments with a buffer chamber 150, for example, in some embodiments, the expansion angle between the second capillary valve 130 and the buffer chamber 150 is greater than or equal to 45°; and / or, the expansion angle between the third capillary valve 160 and the buffer chamber 150 is greater than or equal to 45°. In some embodiments, the expansion angle between the third capillary valve 160 and the second chamber 170 is greater than or equal to 45°; as an example, the expansion angle between the third capillary valve 160 and the second chamber 170 is greater than or equal to 50°. It is understood that the expansion angle, also known as the expansion angle or sudden expansion angle, is the opening angle formed on both sides of the channel when fluid enters a wide cavity, i.e., a wide channel, from a narrow channel.

[0053] This multi-stage expansion angle structure design, on the one hand, sets the expansion angles of the first capillary valve 120 and the first chamber 110, the second capillary valve 130 and the burst valve assembly, and the third capillary valve 160 and the burst valve assembly to be greater than or equal to 45°, with a typical value of greater than or equal to 50°. This creates a significant capillary pressure jump in the centrifugal flow field, constructing a strong and effective fluid blocking barrier. This further prevents backflow of liquid along the capillary valve structure 100, completely avoiding liquid backflow between the chambers of the microfluidic chip 200 at the flow path interface level, and stably ensuring unidirectional fluid conduction and timing control effects. On the other hand, in the embodiment equipped with the buffer chamber 150, setting the expansion angles of the second capillary valve 130 and the buffer chamber 150, and the third capillary valve 160 and the buffer chamber 150 to be greater than or equal to 45°, can synergistically improve the fluid cutoff capability at the interface, weaken the fluid backflow tendency, optimize the smoothness of liquid conduction, reduce local eddies and bubble retention, and improve the control stability and detection repeatability of the capillary valve structure 100. Furthermore, setting the expansion angle between the third capillary valve 160 and the second chamber 170 to no less than 45° and preferably more than 50° can enhance the backflow prevention performance of the end interface, ensuring that the liquid enters the second chamber 170 stably without backflow. As an example, the expansion angle combined with the buffer chamber 150 forms a mutually supportive backflow prevention system. The expansion angle provides controllable burst pressure and a reverse resistance barrier, while the buffer chamber provides pressure release space and reverse containment space. It also has the function of jointly suppressing bubble generation in the forward flow and generating bubbles in the reverse flow to prevent backflow. For the hydrophobic design to be described below, the expansion angle combined with the buffer chamber 150 and the hydrophobic surface provides an even better backflow prevention effect.

[0054] To further prevent backflow of liquid along the capillary valve structure 100 in the centrifugal environment, in some embodiments, such as Figure 1 As shown, the first capillary valve 120 has a curved shape, and the curved shape has at least one inflection point 180; wherein, the inflection point 180 may also be referred to as a corner, turning angle, or bend angle, etc. In some embodiments, the first capillary valve 120 and the second capillary valve 130 have the same or different curved shapes, and the curved shapes have at least one inflection point 180, so that there are at least two inflection points 180 between the first chamber 110 and the burst valve assembly. As an example, the third capillary valve 160 has a curved shape, or as... Figure 1 As shown, the third capillary valve 160 has a straight shape. As an example, the first capillary valve 120 has an obtuse-angled inflection point 180, and the second capillary valve 130 has an acute-angled or right-angled inflection point 180; or, the first capillary valve 120 has an obtuse-angled inflection point 180, and the first capillary valve 120 and the second capillary valve 130 are connected to form an acute-angled or right-angled inflection point 180.

[0055] This multi-stage curved configuration combined with the inflection point 180 design, on the one hand, by setting the first capillary valve 120 with a curved shape containing at least one inflection point 180, and simultaneously enabling the first capillary valve 120 and the second capillary valve 130 to cooperate in forming at least two inflection points 180, constructs a multi-fluid blocking structure in the centrifugal flow field, significantly improving the anti-backflow capability of the capillary valve structure 100. From the perspective of flow path morphology, it completely avoids liquid backflow along the capillary valve structure 100, reliably ensuring the directional liquid transmission between the first chamber 110 and the second chamber 170, and eliminating the risk of backflow between chambers. On the other hand, the first capillary valve 120 and the second capillary valve 130 can adopt the same or different curved configurations, combined with obtuse-angle inflection points 180, acute-angle inflection points 180, and right-angle inflection points 180, which can precisely control the capillary pressure gradient and fluid conduction threshold, adapt to different centrifugation rates and fluid characteristic requirements, and improve the accuracy and flexibility of valve control timing. On the other hand, the third capillary valve 160 can be flexibly selected in either a straight or curved shape, balancing flow path efficiency and structural stability, optimizing fluid delivery smoothness, reducing local resistance and the risk of bubble trapping, and improving the operational reliability of the microfluidic chip 200. Furthermore, this geometric design requires no external drive, heating, or electrical control, maintaining fully passive valve control characteristics. Its simple structure and ease of fabrication effectively reduce chip manufacturing costs and lower the barrier to entry, enhancing the control robustness of the capillary valve structure 100 in centrifugal microfluidic systems. This better meets the core requirements of precise fluid control and stable operation in point-of-care testing scenarios such as POCT, thereby comprehensively improving the overall performance and application versatility of the microfluidic chip 200.

[0056] To increase the contact angle of the capillary valves for controlling liquid flow, in some embodiments, at least one of the first capillary valve 120 and the second capillary valve 130 has a hydrophobic surface; for example, either the first capillary valve 120 or the second capillary valve 130 has a hydrophobic surface; or, both the first capillary valve 120 and the second capillary valve 130 have hydrophobic surfaces. In some embodiments, the third capillary valve 160 has a hydrophobic surface. As an example, the hydrophobic surface is formed by treatment with a hydrophobic reagent.

[0057] This hydrophobic surface modification design has several advantages. First, by applying hydrophobic surface treatment to the first capillary valve 120, the second capillary valve 130, and the third capillary valve 160, the contact angle of the inner walls of each capillary valve is effectively increased. This allows for precise control of capillary pressure, achieving stable passive control of liquid flow and preventing liquid from flowing or stagnating under unexpected conditions, thus enhancing the on / off reliability of the capillary valve structure 100. Second, the hydrophobic surface significantly reduces the adhesion between the liquid and the channel wall, reducing liquid residue, wall adhesion, and bubble adsorption. This ensures smooth directional transport of fluid under centrifugal force, further preventing backflow and inter-chamber backflow of liquid along the capillary valve structure 100 in the centrifugal environment, improving the fluid control accuracy and detection repeatability of the microfluidic chip 200. Third, the hydrophobic surface is formed using hydrophobic reagents, a simple and compatible process that can adapt to the processing requirements of microfluidic chips 200 made of different materials without increasing the complexity of the structure or manufacturing difficulty, maintaining the overall simplicity of the capillary valve structure 100.

[0058] The capillary valve structure 100 is further illustrated below to address the problem of liquid easily flowing back into the previous chamber from one chamber to the next under the influence of Euler force in microfluidic chips 200, especially disc-type microfluidic chips, during operation. Figure 1 As shown, the capillary valve structure 100 includes a first chamber 110, a first capillary valve 120, a second capillary valve 130, a burst valve assembly, a third capillary valve 160, and a second chamber 170. The burst valve assembly includes a burst valve 140 and a buffer chamber 150. As an example, the first chamber 110 is the chamber where the liquid has been transferred. The first capillary valve 120 controls the transfer of liquid from the first chamber 110 to the second chamber 170. The second capillary valve 130, the burst valve 140, the buffer chamber 150, and the third capillary valve 160 prevent liquid from flowing back from the second chamber 170 to the first chamber 110. The second chamber 170 is the chamber where the liquid is located.

[0059] In some embodiments, the first chamber 110 may be circular, elliptical, square, or other shapes, and its shape and structure are mainly determined by its function. The expansion angle between the first chamber 110 and the first capillary valve 120 is greater than 45°.

[0060] In some embodiments, the length, i.e., the depth, of the first capillary valve 120 is between 10 μm and 100 μm, and the shape of the first capillary valve 120 is curved, with one or more inflection points 180. As an example, the surface of the first capillary valve 120 can be treated with a hydrophobic agent to increase its contact angle, thereby better controlling the liquid flow.

[0061] In some embodiments, the depth of the second capillary valve 130 is between 50 μm and 1000 μm, and the shape of the second capillary valve 130 is curved, with one or more inflection points 180. As an example, the surface of the second capillary valve 130 can be treated with a hydrophobic agent to increase its contact angle and better control the liquid flow.

[0062] In some embodiments, the depth of the buffer cavity 150 used to connect the second capillary valve 130 and the third capillary valve 160 is between 0.5 mm and 5 mm, the expansion angle at the connection between the buffer cavity 150 and the second capillary valve 130 is greater than 45°, the expansion angle at the connection between the buffer cavity 150 and the third capillary valve 160 is greater than 45°, and the area of ​​the buffer cavity 150 is greater than 1 mm². 2 The shape of the buffer chamber 150 can be circular, square, or other irregular shapes. As an example, the shape of the buffer chamber 150 is elliptical or monolithic, i.e., racetrack-shaped. This elongated shape can have a larger expansion angle within the same burst valve assembly area, and a larger expansion angle can better prevent liquid backflow.

[0063] In some embodiments, the depth of the third capillary valve 160 is between 100 μm and 1000 μm, and the shape of the third capillary valve 160 can be straight or curved. As an example, the surface of the third capillary valve can be treated with a hydrophobic agent to increase its contact angle, thereby improving control of liquid flow.

[0064] In some embodiments, the depth relationship among the first capillary valve 120, the second capillary valve 130, and the rupture valve assembly is: rupture valve assembly > second capillary valve 130 > first capillary valve 120. The greater the depth difference between the valves, the better the backflow prevention capability. As an example, the depth between the third capillary valve 160 and the rupture valve assembly is: rupture valve assembly > third capillary valve 160. The greater the depth difference between the two valves, the better the backflow prevention capability.

[0065] In some embodiments, the second chamber 170 can be circular, elliptical, square, or other shapes, and its shape and structure are mainly determined by its function. As an example, the expansion angle between the second chamber 170 and the third capillary valve 160 is >45°.

[0066] This design addresses the core issue of liquid backflow between chambers in microfluidic chips under Euler forces. By employing a multi-stage series arrangement of the first chamber 110, first capillary valve 120, second capillary valve 130, burst valve 140, buffer chamber 150, third capillary valve 160, and second chamber 170, a complete passive fluid control pathway is constructed. This structurally prevents liquid from flowing back from the second chamber 170 to the first chamber 110, effectively solving the backflow problem under the combined fields of centrifugal and Euler forces without significantly increasing costs, ensuring stable and controllable fluid timing in the microfluidic chip 200. Furthermore, the first chamber 110 and second chamber 170 can flexibly adopt circular, elliptical, or square shapes to adapt to different functions, combined with an interface expansion angle greater than 45°, strengthening the capillary pressure change at the interface and enhancing the basic backflow prevention capability. On the other hand, the first capillary valve 120, the second capillary valve 130, and the third capillary valve 160, with their curved configuration and at least one inflection point 180, combined with a high contact angle hydrophobic surface formed by hydrophobic reagent treatment, precisely control the liquid conduction and cutoff states, reducing the risk of adhesion and air bubbles. Furthermore, the buffer chamber 150 has been optimized with two expansion angles greater than 45°, achieving greater backflow prevention capability within the same area, while also providing flow stabilization, buffering, and fluid shock elimination. Simultaneously, the depth gradient design of the buffer chamber 150, the second capillary valve 130, and the first capillary valve 120, as well as the depth gradient design of the buffer chamber 150 and the third capillary valve 160, strengthens the pressure barrier through depth differences, effectively improving the backflow prevention effect.

[0067] In some embodiments, a microfluidic chip 200, such as Figure 2 As shown, it includes a substrate 210 and a capillary valve structure 100 as described in any embodiment, wherein the capillary valve structure 100 is disposed on the substrate 210. It is understood that, since the capillary valve structure 100 as described in any embodiment is used, the microfluidic chip 200 also has the beneficial technical effects of the capillary valve structure 100, which will not be elaborated here.

[0068] It should be noted that, Figure 2 This is merely a simplified illustration of a microfluidic chip 200 employing a capillary valve structure 100. In practical applications, the microfluidic chip 200 may also have other chambers or other structures, and this application does not impose any additional limitations on this embodiment.

[0069] It should be noted that other embodiments of this application also include capillary valve structures and microfluidic chips that can be implemented by combining the technical features of the above embodiments.

[0070] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0071] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the patent protection scope of this application should be determined by the appended claims.

Claims

1. A capillary valve structure, characterized in that, It includes a first capillary valve (120), a second capillary valve (130), a burst valve assembly, and a third capillary valve (160) connected in sequence. The first capillary valve (120) is configured to also connect to the first chamber (110), and the third capillary valve (160) is configured to also connect to the second chamber (170) to transfer liquid in the first chamber (110) to the second chamber (170) under centrifugal action. The length of the burst valve assembly is greater than the lengths of the second capillary valve (130) and the third capillary valve (160), and the length of the second capillary valve (130) is greater than the length of the first capillary valve (120).

2. The capillary valve structure according to claim 1, characterized in that, The sum of the volumes of the first capillary valve (120), the second capillary valve (130), and the third capillary valve (160) is less than the volume of the burst valve assembly; or, The maximum passing area of ​​any one of the first capillary valve (120), the second capillary valve (130), and the third capillary valve (160) is less than the maximum passing area of ​​the burst valve assembly.

3. The capillary valve structure according to claim 1, characterized in that, The expansion angle between the first capillary valve (120) and the first chamber (110) is greater than or equal to 45°; or, The expansion angle between the second capillary valve (130) and the burst valve assembly is greater than or equal to 45°; or, The expansion angle between the third capillary valve (160) and the burst valve assembly is greater than or equal to 45°; or, The expansion angle between the third capillary valve (160) and the second chamber (170) is greater than or equal to 45°.

4. The capillary valve structure according to claim 1, characterized in that, The first capillary valve (120) and the second capillary valve (130) have the same or different curved shapes, and the curved shapes have at least one inflection point (180); or, At least one of the first capillary valve (120) and the second capillary valve (130) has a hydrophobic surface; or, The third capillary valve (160) has a hydrophobic surface.

5. The capillary valve structure according to claim 1, characterized in that, The length of the first capillary valve (120) is 10 μm to 100 μm; or, The length of the second capillary valve (130) is 50 μm to 1000 μm; or, The length of the third capillary valve (160) is 100 μm to 1000 μm.

6. The capillary valve structure according to claim 1, characterized in that, The maximum passage area of ​​the rupture valve assembly is greater than 1 square millimeter; and / or The length of the rupture valve assembly is 0.5 mm to 5 mm.

7. The capillary valve structure according to claim 1, characterized in that, The burst valve assembly includes a burst valve (140) and a buffer chamber (150), wherein the buffer chamber (150) is connected to the second capillary valve (130), the burst valve (140) and the third capillary valve (160).

8. The capillary valve structure according to claim 7, characterized in that, The buffer cavity (150) is flat and has a short length in the centrifugal radial direction.

9. The capillary valve structure according to any one of claims 1 to 8, characterized in that, The capillary valve structure further includes at least one of the first chamber (110) and the second chamber (170).

10. A microfluidic chip, characterized in that, It includes a substrate (210) and a capillary valve structure as described in any one of claims 1 to 9, the capillary valve structure being disposed on the substrate (210).

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